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<TITLE>UW Constraint-Based Languages and Systems</TITLE>
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<H1>UW Constraint-Based Languages and Systems</H1>

Welcome to the home page for Constraints at 
<!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><!WA0><A HREF="http://www.cs.washington.edu/">UW CSE</A>.

<P>  

A constraint is a relation that should be satisfied; for example, that a line
remain horizontal, that a resistor in an electrical circuit simulation
obey Ohm's Law, or that the height of a bar in a bar chart be proportional
to some number in an application program.  Constraints have been used in a
variety of languages and systems, particularly user interface toolkits,
in planning and scheduling, and in simulation.

<p>

Our research is in several areas: 
<UL>
<LI>constraint imperative programming, in particular the 
   Kaleidoscope language
<LI>constraint logic programming, in particular the HCLP language scheme
<LI>constraint hierarchies
<LI>constraint solvers
<LI>using constraints in user interface construction
</UL>

<hr>

<h2>People</h2>

Faculty:

<UL>

<LI><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><!WA1><a href="http://www.cs.washington.edu/homes/borning">Alan Borning</a>,
<em>borning@cs.washington.edu</em>

</UL>

Current Students:

<UL>

<LI><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><!WA2><a href="http://weber.u.washington.edu/~hildrum">Kirsten Hildrum</a>,
<em>hildrum@cs.washington.edu</em>

<LI><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><!WA3><a href="http://www.cs.washington.edu/homes/lopez">Gus Lopez</a>,
<em>lopez@cs.washington.edu</em>

<LI><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><!WA4><a href="http://www.cs.washington.edu/homes/montgmry">Andy
Montgomery</a>, <em>montgmry@cs.washington.edu</em>

</UL>

Alumni:

<UL>

<LI>Jeffrey Berg

<LI>Scott Bradley

<LI>Rob Duisberg

<LI>Bjorn Freeman-Benson, <em>bnfb@oti.com</em>

<LI>Axel Kramer

<LI>John Maloney

<LI>Amy Martindale

<LI>Sean McAteer, <em>smcateer@cs.washington.edu</em>

<LI>David Nagy-Farkas, <em>davidnf@cs.washington.edu</em>

<LI>Michael Sannella, <em>sannella@faline.bellcore.com</em>

<LI>Paul Williams

<LI>Molly Ann Wilson

<LI>Michael Woolf

</UL>

<hr>
<H2>Papers</H2>

The following list contains citations for recent papers.  Click on a title
to go to that paper's page, containing an abstract and a link to the
postscript file.

<P>

<h3>Constraint Imperative Programming</h3>

<UL>

<LI>Bjorn Freeman-Benson and Alan Borning, 
<!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><!WA5><a href="http://www.cs.washington.edu/research/projects/weird/www/kaleidoscope-iccl-92.html"> "The Design and Implementation of
Kaleidoscope'90, A Constraint Imperative Programming Language"</a>,
<em>Proceedings of the IEEE Computer Society 1992 International Conference
on Computer Languages</em>, April 1992, pages 174-180.

<LI>Bjorn Freeman-Benson and Alan Borning,
<!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><!WA6><a href="http://www.cs.washington.edu/research/projects/weird/www/kaleidoscope-ecoop-92.html"> "Integrating Constraints with an
Object-Oriented Language"</a>, Proceedings of the 1992 European Conference
on Object-Oriented Programming, June 1992, pages 268-286.

<LI>Gus Lopez, Bjorn Freeman-Benson, and Alan Borning, 
<!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><!WA7><a href="http://www.cs.washington.edu/research/projects/weird/www/kaleidoscope-asi.html"> "Kaleidoscope: A Constraint Imperative
Programming Language"</a>, In <em>Constraint Programming</em>, B. Mayoh,
E. Tougu, J. Penjam (Eds.), NATO Advanced Science Institute Series, Series
F: Computer and System Sciences, Vol 131, Springer-Verlag, 1994, pages
313-329.

<LI>Gus Lopez, Bjorn Freeman-Benson, and Alan Borning,
<!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><!WA8><a href="http://www.cs.washington.edu/research/projects/weird/www/kaleidoscope-ecoop-94.html"> "Constraints and Object
Identity"</a>, Proceedings of the 1994 European Conference on
Object-Oriented Programming, Bologna, Italy, July 1994, pages 260-279.

<LI>Gus Lopez, Bjorn Freeman-Benson, and Alan Borning,
<!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><!WA9><a href="http://www.cs.washington.edu/research/projects/weird/www/kaleidoscope-oopsla-94.html"> "Implementing Constraint Imperative
Programming Languages: the Kaleidoscope'93 Virtual Machine"</a>,
Proceedings of the 1994 ACM Conference on Object-Oriented Programming
Systems, Languages, and Applications, Portland, Oregon, October 1994, pages
259-271.

</UL>

<P>

<HR>

<h3>Hierarchical Constraint Logic Programming</h3>

<UL>

<LI>Alan Borning, Michael Maher, Amy Martindale, and Molly Wilson,
<!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><!WA10><a href="http://www.cs.washington.edu/research/projects/weird/www/hclp-iclp-89.html"> "Constraint Hierarchies and Logic
Programming"</a>, Proceedings of the Sixth International Logic Programming
Conference, Lisbon, Portugal, June 1989, pages 149-164.

<LI>Molly Wilson and Alan Borning, <!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><!WA11><a href="http://www.cs.washington.edu/research/projects/weird/www/extending-hclp-naclp-89.html">
"Extending HCLP Languages: Nonmonotonicity and Inter-Hierarchy
Comparison"</a>, Proceedings of the 1989 North American Logic Programming
Conference, Cleveland, October 1989, pages 3-19.

<LI>Molly Wilson and Alan Borning, <!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><!WA12><a href="http://www.cs.washington.edu/research/projects/weird/www/jlp-93.html"> "Hierarchical
Constraint Logic Programming"</a>, The Journal of Logic Programming,
special issue on Constraint Logic Programming, Vol. 16 Nos. 3 & 4,
July-August 1993, pages 227-318.

<LI>Molly Ann Wilson, <!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><!WA13><a href="http://www.cs.washington.edu/research/projects/weird/www/wilson-phd.html"> "Hierarchical Constraint
Logic Programming"</a>, PhD dissertation, April 1993.

</UL>

<P>

<HR>

<h3>Constraint Solvers</h3>

<UL>

<LI>Michael Sannella, <!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><!WA14><a href="http://www.cs.washington.edu/research/projects/weird/www/skyblue-tr-92.html"> "The SkyBlue
Constraint Solver"</a>, UW tech report 92-07-02.

<LI>Michael Sannella, John Maloney, Bjorn Freeman-Benson, and Alan
Borning, <!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><!WA15><a href="http://www.cs.washington.edu/research/projects/weird/www/spe-deltablue-93.html"> "Multi-way versus One-way
Constraints in User Interfaces: Experience with the DeltaBlue
Algorithm"</a>, Software--Practice and Experience, Vol. 23 No. 5, (May
1993), pages 529-566.

<LI>Michael Sannella, <!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><!WA16><a href="http://www.cs.washington.edu/research/projects/weird/www/skyblue-ppcp-93.html"> "The Skyblue
Constraint Solver and Its Applications"</a>, Vijay Saraswat
and Pascal van Hentenryck, editors, Proceedings of the 1993 Workshop on
Principles and Practice of Constraint Programming, MIT Press, 1995, pages
385-406.

<LI><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><!WA17><a href="http://www.cs.washington.edu/research/projects/weird/www/skyblue-cycles.html">Problem with SkyBlue and Cycles</a>.

<LI>Alan Borning and Bjorn N. Freeman-Benson, 
<!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><!WA18><a href="http://www.cs.washington.edu/research/projects/weird/www/ultraviolet-cp-95.html"> "The OTI Constraint Solver: A Constraint
Library for Constructing Interactive Graphical User Interfaces"</a>, 
<em>Proceedings of the First International Conference on
Principles and Practice of Constraint Programming</em>, September 1995,
pages 624-628.

<LI>Alan Borning, Richard Anderson, and Bjorn Freeman-Benson, 
<!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><!WA19><a href="http://www.cs.washington.edu/research/projects/weird/www/indigo-uist-96.html"> "Indigo: A Local Propagation Algorithm for
Inequality Constraints"</a>, <em>Proceedings of the 1996 ACM Symposium on
User Interface Software and Technology</em>, pages 129-136.  A companion
technical report, <!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><a href="http://www.cs.washington.edu/research/projects/weird/www/indigo-tr.html"> "The Indigo Algorithm"</a>, UW
tech report 96-05-01, contains additional material (proofs of theorems and
definitions of interval operations).




</UL>

<P>

<HR>

<h3>Theory of Constraint Hierarchies</h3>

<UL>

<LI>Alan Borning, Bjorn Freeman-Benson, and Molly Wilson, 
<!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><a href="http://www.cs.washington.edu/research/projects/weird/www/hierarchies-92.html"> "Constraint Hierarchies"</a>,
Lisp and Symbolic Computation, Vol. 5 No. 3, (September 1992), pages
223-270.

</UL>

<P>

<HR>

<h3>Constraints and User Interfaces</h3>

<UL>

<LI>Bjorn Freeman-Benson, <!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><a href="http://www.cs.washington.edu/research/projects/weird/www/cooldraw-uist-93.html"> "Converting an
Existing User Interface to Use Constraints"</a>, <em>Proceedings of the
1993 ACM Symposium on User Interface Software and Technology</em>, Atlanta,
Georgia, November 1993, pages 207-215.

<LI>Michael Sannella and Alan Borning, <!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><a href="http://www.cs.washington.edu/research/projects/weird/www/multi-garnet-92.html">
"Multi-Garnet: Integrating Multi-Way Constraints with Garnet"</a>, UW tech
report 92-07-01.

<LI>Michael Sannella, <!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><a href="http://www.cs.washington.edu/research/projects/weird/www/debugging-ppcp-94.html"> "Analyzing and
Debugging Hierarchies of Multi-Way Local Propagation Constraints"</a>, in
Alan Borning (ed.), <em>Proceedings of the 1994 Workshop on Principles and
Practice of Constraint Programming</em>, Springer-Verlag, Lecture Notes in
Computer Science No. 874, pages 63-77.

<LI>Michael Sannella, <!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><a href="http://www.cs.washington.edu/research/projects/weird/www/sannella-phd.html"> "Constraint
Satisfaction and Debugging for Interactive User Interfaces"</a>, PhD
dissertation, August 1994.  Revised version published as UW Tech Report
94-09-10.

<LI>Michael Sannella, <!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><a href="http://www.cs.washington.edu/research/projects/weird/www/skyblue-uist-94.html"> "SkyBlue: A
Multi-Way Local Propagation Constraint Solver for User Interface
Construction"</a>, in <em>Proceedings of the 1994 ACM Symposium on User
Interface Software and Technology</em>, pages 137-146.

</UL>

<hr>
<H2>Funding</H2>

This research is currently supported in part by two grants from the 
<!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><a href="http://www.nsf.gov">National Science Foundation</a>:
"Constraint-Based Languages and Environments for Building Interactive
Systems", Grant No. IRI-9302249, Interactive Systems Program, and
"Constraint Imperative Programming", Grant No. CCR-9402551, Programming
Languages and Compilers Program.  The work on constraint satisfaction
algorithms and libraries is supported in part by 
<!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><a href="http://www.oti.com">Object Technology International</a>.

<P>

<hr>
<H2>Other Resources</H2>

We also maintain an <!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><a href="ftp://ftp.cs.washington.edu/pub/constraints">
anonymous ftp directory</a> at UW on
<code>//ftp.cs.washington.edu/pub/constraints</code>.  The 
<!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><a href="ftp://ftp.cs.washington.edu/pub/constraints/code"> code</a>
subdirectory contains source code for various constraint solvers and
systems, including DeltaBlue and SkyBlue.  All this code is public domain.
The <!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><a href="ftp://ftp.cs.washington.edu/pub/constraints/ppcp94">
ppcp94</a> subdirectory contains papers from the 1994 Principles and
Practice of Constraint Programming Workshop.  There is a
<!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><a href="ftp://ftp.cs.washington.edu/pub/constraints/papers">
papers</a> subdirectory with research papers (but all of the
papers are also listed in this WWW document, so don't bother).
Finally, there is a 
<!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><a href="ftp://ftp.cs.washington.edu/pub/constraints/drafts">
drafts</a> subdirectory, which sometimes contains preliminary drafts of
papers.

<p>

For more general information on constraints, and links to lots of
interesting stuff, see the <!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><a href="http://www.cirl.uoregon.edu/constraints">
Constraints Archive page</a>.

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<hr>

<address>
borning@cs.washington.edu <br>
</address>
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